A vicar has been found guilty of conducting sham marriages to allow illegal immigrants to stay in Britain.

The Rev Alex Brown conducted the "massive and cynical scam" over a four-year period which involved hard-up Eastern Europeans being paid up to £3,000 to marry Africans.

The 61-year-old conducted a total of 383 marriages at the Church of St Peter and St Paul in St Leonards-on-Sea, East Sussex, between July 2005 and July 2009. During this period there was a staggering 30-fold increase on the number of marriages conducted over the previous four years. Prosecutors believe the vast majority were shams.

Following a seven-week trial at Lewes Crown Court jurors found him guilty of a charge of conspiring to facilitate the commission of breaches of immigration laws, along with co-defendants, Michael Adelasoye, 50, and Vladymyr Buchak, 33.

The gang were caught following an investigation by the UK Border Agency (UKBA) after caseworkers noticed the huge number of immigration applications involving people who had got married at the church. The scam was described by a Crown Prosecution Service (CPS) spokesman as the largest sham marriage racket his team had ever prosecuted.

Detective Inspector Andy Cummins, of the UKBA's South East region immigration crime team, said the investigation was "unprecedented", describing the three men as "happy to exploit and take advantage of other people's desperation for their own ends".

Jurors heard that Buchak, a Ukrainian national who had himself been living illegally in the UK since at least 2004, was responsible for "cajoling and persuading" the Eastern Europeans into the marriages of convenience. He preyed on migrant workers who were living in the area and were desperate to earn money by offering them cash to wed the Africans, mainly from Nigeria.

Although Buchak was seen as the principal organiser of the operation, prosecutor David Walbank said there was no doubt that Brown must have been fully aware that the majority of the weddings he was conducting at the church were shams. Brown was suspended from his duties after his arrest and may now face disciplinary action from the Church.

He was arrested on June 30 last year and his vicarage home in Blomfield Road, St Leonards-on-Sea, and the church were searched. Investigators found documents he had doctored including the church's electoral roll plus a second, altered copy, which he had filled out to hide the dramatic increase in weddings he was presiding over.

Following the verdicts, the Archdeacon of Lewes and Hastings, Philip Jones, said Brown, who was ordained as a priest in 1983, had committed a "betrayal of trust" towards his congregation and the wider community. He said: "We are particularly sorry for those who have been deceived and hurt by the actions of Father Alex Brown. The church and the community of St Leonards-on-Sea are faced with a betrayal of trust on the part of Father Alex Brown."